IT HAPPENED in a flash: The gorilla hurtled through the trees and made a beeline for me.

I froze as several hundred pounds of primate thundered my way. But instead of attacking, Kalembezi, a juvenile, lightly nipped my leg and disappeared into the thick vegetation.

Robin Kawakami braved safari ants and stinging nettles to track mountain gorillas in their native habitat in Bwindi Impenetrable National Park in southwestern Uganda. She joins Lunch Break with her story. Photo: David S. Lee.

Peals of laughter broke out behind me as I tried to process what had happened. Our guide,
Obed Tukwasibwe,
who tracks gorillas for a living and had witnessed Kalembezi's antics before, could hardly contain his delight. "He is the mischievous one," he exclaimed, as I tried to play down my alarm.

Mountain gorillas are highly social creatures and among the world's largest primates. Naturalist
Dian Fossey
famously studied them in Rwanda. And they are now so endangered that they can only be found in three places: Rwanda, the Democratic Republic of Congo and Uganda. (Mountain gorillas don't fare well in captivity; the ones found in zoos are mostly the lowland variety.) Kalembezi's home is Bwindi Impenetrable National Park, an 80,000-acre rain forest reserve in southwestern Uganda where about 400 mountain gorillas—nearly half the world's population—live.

Photos: Close Encounters of the Primate Kind

Click to view slideshow. David S. Lee

The mountain gorilla's dwindling numbers are in part a reflection of their volatile homeland. War, rebellion and political unrest have all led to habitat destruction and the killings of game wardens and gorillas. But today Uganda is stable and relatively safe—and tourist numbers are on the rise, with visitors doubling to over a million from 2006 to 2011, according to the Uganda Bureau of Statistics.

Still, reaching the misty mountains of Bwindi is neither easy nor cheap. My husband, David, and I took multiple long-haul flights, rode for hours over dirt roads in a four-wheel-drive vehicle and paid $500 each for permits to hike through a hilly, humid, hazard-filled forest in search of these special creatures—and, if we found them, to spend just an hour in their company.

"The shortest trek took 10 minutes," one of the Bwindi wardens told us on the day we visited the park. Most were far longer, he said, trying to set expectations for our group. Two women we were hiking with had spent 14 hours the previous day searching for gorillas.

‘'The silverback's coming down!' our guide warned. 'Stay together.'’

As their name implies, the gorillas live in mountains—peaks that reach thousands of feet above sea level and are thick with vegetation—and so can only be tracked on foot. (Some visitors will even hire porters to carry them up the mountains.) Stinging nettles, safari ants and steep, slippery slopes are par for the course. The gorillas are nowhere near as abundant as elephants, Cape buffalo or other animals you might see on a classic African safari. And to top it off, they are fast-moving targets, known to travel several miles overnight.

There are about a dozen gorilla families in the park; some are not habituated to humans and are likely to become agitated if approached in the wild. Bwindi strictly limits the number of visitors to the park, issuing a maximum of eight permits per gorilla family per day. We were assigned to the Rushegura clan.

Hiking in the park
David S. Lee

There were some experienced, intrepid travelers on our team: One man had climbed Mount Everest, and a woman had sailed around the globe. But we were all still buzzing with excitement that morning. Mr. Tukwasibwe laid out the rules. If we found the gorillas, we would have one hour with them. Flash photography, eating and drinking were prohibited. We had to keep at least seven meters (23 feet) away, unless a gorilla approached us. And, since gorillas share 98.4% of our DNA, anyone feeling unwell would be barred from the hike so we wouldn't infect them.

"You'll want to pull socks over your pant legs," Mr. Tukwasibwe warned. Safari ants can quickly climb up under pants and inflict painful bites. We wore thick leather gloves to protect from the stinging nettles that can tear through clothing and skin. Most of us carried walking sticks for the uneven terrain, though these would have to be set aside just before seeing the gorillas, who can become distressed around people with objects that might be weapons.

"Stay close together, as one unit," Mr. Tukwasibwe advised. And if a gorilla approached—particularly the silverback, the dominant adult male gorilla with distinctive gray fur on its back—we were to adopt a submissive position, looking down and avoiding eye contact, to avoid provoking him. We heard a cautionary tale about a silverback who had charged after a photographer failed to adhere to the no-flash rule.

A baby gorilla
Katrina Martlew

We set off at an easy pace, following a trail into the forest. At first glance, the tall trees looked like any you might find in the Pacific Northwest. But the unusual birdcalls, clicks and other curious sounds—not to mention the supersize bugs—quickly dispelled that illusion. The sun shone brightly through the canopy, making the previous day's showers a distant memory. Men with machetes and AK-47s—protection against a rogue gorilla or guerrillas from the neighboring Democratic Republic of Congo—accompanied us, along with a team of local villagers a few of us had hired to carry our packs for $15.

About an hour and a half into the hike, Mr. Tukwasibwe's radio crackled: Our family had been spotted nearby. This trek wouldn't be a 12-hour expedition.

We stepped off the trail and plunged into the forest, which was impenetrable enough to live up to its name. The men with machetes cleared a passage just wide enough for one person to pass through. Branches and nettles clung to our heads and sleeves, and the uneven forest floor gave way at inopportune times. I concentrated intensely on each footfall, forgetting our ultimate goal, until I saw it—or her—sitting on the forest floor in a small clearing.

About 10 feet away from us, a female gorilla was delicately picking apart and eating a piece of Myrianthus holstii, a fruit that resembles a large artichoke. She glanced at us without pausing in her task. It has been said that making eye contact with mountain gorillas gives you the distinct sense that they possess self-awareness. But what captured my attention—and made them seem very much like humans—was how they used their hands.

Suddenly, a softball-size object whizzed by my head and hit the forest floor with a thud. "Watch out," said my husband, as we covered our heads with our hands. Dark figures darted among the branches above us, as more pieces of fruit rained down.

Desperately Seeking Species

More spots to see rare animals

India: Asiatic Lions There are thought to be just 411 of these big cats left, found in the wild only in northwestern India. Gujarat's Gir Forest National Park provides three-hour jeep safaris from October through mid-June. gujaratforest.org

China: Giant Pandas According to the World Wildlife Fund, there are fewer than 1,600 pandas left, mostly in the mountains of west-central China. Outfitter WildChina offers a nine-day tour that includes trekking in Wanglang Nature Reserve, also home to golden monkeys and red pandas. From $3,930 per person, wildchina.com

New England: Whales Whale-watching trips run by Boston Harbor Cruises and the New England Aquarium offer minke, humpback and finback sightings off the coast of Massachusetts. The very lucky might even glimpse a Northern Right Whale, so endangered that fewer than 350 remain. $45 for adults, bostonharborcruises.com

—Sara Clemence

We held our breath as a nearby tree branch strained under the weight of a descending gorilla. "The silverback's coming down!" said Mr. Tukwasibwe. "Stay together." The massive alpha came into view and coolly surveyed us. Everything seemed to come to a standstill. Even the other gorillas paused to see what he would do. Flashbacks of "When Animals Attack!" began to run through my head.

But the silverback quietly turned away and descended into a clearing. The clan followed in a line, and we joined them for about 100 feet or so. As the terrain steepened, the gorillas dispersed into the forest. Foliage obscured our vision—and it was then that Kalembezi ambushed me.

It was the kind of moment that pushed the rest of the trek into the background. For the remaining part of the hour, the gorillas came incredibly close to us—sometimes as near as three feet. They swung from vines, climbed trees and beat their chests. They even seemed to enjoy having an audience. The baby, Kabunga, hopped onto a fallen log and pranced back and forth, mugging for our cameras. In what appeared to be a tender moment, an adult gorilla put her arms around a juvenile, only to steal a piece of fruit right out of the youngster's hands.

After a while, the gorillas seemed to sense that our golden hour was almost over. The silverback got up and crossed a nearby bridge, disappearing into the shadows. One by one, the gorillas trailed him, briefly making eye contact with us as they passed. This time, we would not follow.

The Lowdown : Bwindi Impenetrable National Park, Uganda

Getting There: A number of intercontinental airlines fly to Entebbe International Airport, just outside the Ugandan capital of Kampala. Most visitors from the U.S. fly into Entebbe and drive (12 to 15 hours) or fly (about one hour) to Bwindi Impenetrable National Park. Kampala-based AA Safaris arranged transportation and secured gorilla permits for this trip. adventureugandasafari.com

When to Go: Mountain gorillas can be seen year-round, but the best times to visit are December to March and June to September—outside of the main rainy seasons.

Where to Stay: Nkuringo Gorilla Camp offers basic safari tents from $35 per night (nkuringocampsite.com). The upscale Sanctuary Gorilla Forest Camp has eight thatch-roof tents and a small spa (from $325 per person per night, sanctuaryretreats.com). Mahogany Springs, a luxury boutique lodge, has seven suites and runs on hydropower. From $205 per person per night, mahoganysprings.com

Other Things to Do: Lodges can arrange village walks, on which you can meet members of the Batwa pygmy tribe and sample locally distilled banana gin. A white-water rafting trip at the source of the Nile River in Jinja, a couple of hours from Kampala, is worthwhile. $125 per person for a full-day trip, nalubalerafting.com